Oscillator Circuit Layout Using Overlapped MIM Capacitors
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Solution Overview
Problem
The challenge lies in efficiently disposing a layout of capacitors with a metal-insulator-metal (MIM) structure in circuit devices while maintaining wide coupling wiring widths to prevent signal attenuation, which often results in increased circuit area and parasitic capacitance, affecting the oscillation circuit's performance.
Innovation Solution
The capacitors with an MIM structure are overlapped with the coupling wiring in a plan view orthogonal to the substrate, effectively utilizing the wiring area to reduce circuit size and prevent parasitic capacitance, while maintaining wide wiring widths to minimize signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling wiring width is increased to prevent signal attenuation, then the wiring resistance is reduced, but the circuit area increases and parasitic capacitance increases
Solution Approach 1:
The capacitor is positioned in the vertical dimension by overlapping with the coupling wiring in the plan view, allowing the capacitor to occupy space above or below the wiring plane. This dimensional transition enables the capacitor to be integrated without increasing the lateral circuit area, while the wide coupling wiring maintains low resistance for reliable signal transmission.
2Reliability
If the coupling wiring width is increased to prevent signal attenuation, then the wiring resistance is reduced, but the parasitic capacitance increases affecting oscillation circuit performance
Solution Approach 1:
The capacitor, which could be considered a parasitic element when separately disposed, is intentionally integrated by overlapping with the coupling wiring. This converts what would be additional parasitic capacitance into a useful load capacitance element, eliminating the need for separate capacitor structures and reducing overall parasitic effects on the oscillation circuit while maintaining wide wiring for low resistance.
3Device complexity
If capacitors with MIM structure are disposed separately from coupling wiring, then the layout is simpler, but the circuit area increases
Solution Approach 1:
The capacitor structure is merged with the coupling wiring by positioning the capacitor to overlap with the wiring in the plan view. This merging integrates two previously separate elements (capacitor and wiring) into a combined structure, reducing the total circuit area while maintaining the functional independence of both components through their vertical separation.
4Object-generated harmful factors
If capacitors with MIM structure are disposed separately from coupling wiring, then the parasitic capacitance is reduced, but the circuit area increases
Solution Approach 1:
The capacitor is positioned in the vertical dimension by overlapping with the coupling wiring in the plan view, allowing the capacitor to occupy space above or below the wiring plane. This dimensional transition enables the capacitor to be integrated without increasing the lateral circuit area, while the wide coupling wiring maintains low resistance for reliable signal transmission.
Data Source
AI summary
Provided is a circuit device including: a first terminal electrically coupled to one end of a vibrator; a second terminal electrically coupled to the other end of the vibrator; a first coupling wiring electrically coupled to the first terminal; a second coupling wiring electrically coupled to the second terminal; an oscillation circuit having a drive circuit for driving the vibrator via the first coupling wiring and the second coupling wiring, and oscillating the vibrator; and a first capacitor having a metal-insulator-metal (MIM) structure of which one electrode is electrically coupled to the first coupling wiring. The first coupling wiring and the first capacitor having the MIM structure overlap each other in plan view in a direction orthogonal to a substrate on which a circuit element is formed.